The present invention relates generally to making signal strength measurements, and more particularly to making signal strength measurements during variable snapshot periods.
Handover operations in a wireless network often rely on signal strength measurements collected by the mobile stations in the network. For example, mobile stations may measure the strength of signals received from base stations in a serving cell and one or more neighbor cells. A mobile station may assist with handover operations by reporting the measured signal strengths to the network. Alternatively, a mobile station may direct handover operations by requesting handover based on the measured signal strengths.
In conventional networks, the mobile station typically samples and measures the strength of the received signal for a fixed period, referred to herein as the snapshot period. The conventional practice may lead to problems. For example, the Long Term Evolution (LTE) of the Third Generation Partnership Project (3GPP), which may use Orthogonal Frequency Division Multiplexing (OFDM) to implement wireless communications between mobile stations and a wireless network, is expected to allow flexible signal bandwidths from 1.25 MHz to 20 MHz by allocating a variable number of subcarriers. Proposed signal bandwidths currently include 1.25, 1.6, 2.5, 5, 10, 15, and 20 MHz. When the snapshot period is fixed, the number of samples or measurements depends on the signal bandwidth and the length of the snapshot period. For narrow signal bandwidths, the snapshot periods should be long enough to allow a sufficient number of samples to be taken to obtain a reliable estimate of the signal strength. Because the number of samples increases with signal bandwidth, the processing speed or processing capacity needs to be high enough to process measurements for wide signal bandwidths. In some cases, this causes the mobile station to process an unnecessarily large amount of data, and therefore, to expend an unnecessarily large amount of current.